Apoptosis of enterocytes induced by inoculation of a strain of attaching and effacing Escherichia coli and verotoxin.

When verotoxin (VT)-producing attaching and effacing Escherichia coli (AEEC, serotype O5: H-) were inoculated perorally into 10-day-old rabbits, attaching of the E. coli to enterocytes and effecting of their microvillous portion were observed extensively from the ileum to the colon. Subsequent apoptotic changes of the infected enterocytes were demonstrated by the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL) reaction and electron microscopy. Apoptosis was also induced in cultured Vero cells by inoculation of VT extracted from the AEEC. This study clarified that VT-producing AEEC induce apoptosis of enterocytes, causing mucosal damage.